And yep, I now also own many 6502 based computers :-)
I ended up giving away the Joust machine to a guy (https://web.archive.org/web/20200709102945/http://www.robotr...) who had poured his heart and soul into Robotron disassembly and also happened to be the Joust world-record holder in 1983, so I knew he'd appreciate it at least as much as I did. He happened to live in the area, and was more than happy to drive over and load it up. It's been 13 years since then. I hope he and it are doing well!
Factoid: It takes about six hours to reach 10 million points on Joust. Christian's record was 98 million points!
I know, you have to take a pragmatic approach… but feels like cheating… idk.
It also didn't help that I didn't have many EEPROMs or an EEPROM programmer at the time, but the ATMega32A can be programmed with an ordinary Arduino.
[0] - https://hackaday.io/project/19000-a-4-4ics-z80-homemade-comp...
Consider this a warning though: this hobby has caused me to involuntarily collect every model of Z80 powered TRS-80 computer.
If you wish to become hooked anyway, this project might be another good place to start: https://hackaday.io/project/159973-z80-mbc2-a-4-ics-homebrew...